1. Field of the Invention
The invention relates to a piston engine that uses a gas bearing interposed between a piston and a cylinder.
2. Description of the Related Art
Recent years have witnessed growing interest in Stirling engines, which have excellent theoretical thermal efficiency, for recovering waste heat from internal combustion engines installed in cars, buses, trucks and the like, and for recovering waste heat in factories. Japanese Patent Application Publication No. 2005-106009 (JP-A-2005-106009) discloses a Stirling engine in which a gas bearing is interposed between a piston and a cylinder, and in which a piston is supported by an approximate linear mechanism. The Stirling engine disclosed in JP-A-2005-106009 is a piston engine in which a piston executes a reciprocating motion in a cylinder, with a gas bearing interposed in the small clearance between the piston and the cylinder. As a result, the piston and the cylinder might come into contact with each other during stopping of the Stirling engine.